1. Field of the Invention
The present invention is directed to a method and additive for the clarification of an aqueous system which may contain an oil-in-water emulsion, or a dispersion of a non-aqueous discontinuous phase, such as a production stream from a subterranean oil or gas well, such that the emulsion is effectively broken or de-emulsified, or the dispersion resolved, with the resultant aqueous stream being clarified, all without the production of an uncontrollable floc, using a composition having present a dithiocarbamate of bishexamethylenetriamine, wherein the ratio of carbon disulfide to primary amine in the bishexamethylenetriamine is approximately stoichiometric.
2. Brief Description of the Prior Art
The present invention is directed to the clarification of an aqueous system, such that the resultant stream of the aqueous system contains essentially two separate phases: an oil-, or hydrocarbon-based phase, or non-aqueous phase, and an essentially aqueous phase, with the resultant aqueous phase being clarified without production of an uncontrollable floc. Such aqueous systems may be found when producing subterranean oil and/or gas wells. The aqueous systems' may also be any aqueous system sometimes containing an oil-in-water emulsion or a non-aqueous discontinuous phase, in any other commercial or industrial environment, such as: those found in steam cylinder dispersions in which small amounts of oils which are used for lubrication purposes may be found dispersed in steam in engines and pumps; emulsions and other dispersions containing polystyrene and styrene-in-water frequently found in synthetic rubber manufacturing facilities; emulsions and other dispersions obtained during clay pipe manufacture using steam initiated processes and procedures; oil-in-water emulsions or dispersions which are found in coolant water devices and in gasoline absorption facilities; emulsions and dispersions containing wax-type products which are encountered in oil refinery dewaxing procedures; "fluxoil" emulsions and dispersions occurring in condensate steam resulting in dehydrogenation of butylene during catalytic procedures to produce butadiene; emulsions and dispersions obtained during procedures for making butadiene from naptha by means of standard "cracking" procedures in gas generators; emulsions and dispersions of latex-in-water formed in copolymerization procedures for butadiene and styrene derivatives.
Such dispersions and emulsions are also problems in synthetic resin paint and pigment manufacturing processes, as well as in food processing of derivatives of pasturized additives. In each of these processes, as well as in the equipment which is used during steps in the various procedures, oil-in-water emulsions or dispersions of a non-aqueous phase are inherently formed as a by-product of the particular given operation. The disposal of the produced waste water becomes a problem which is compounded by the presence of the oil-in-water emulsions, or dispersions containing a non-aqueous discontinuous phase.
The aqueous systems contemplated in this invention will contain water in various forms, such as tap water, brines or seawater (in the case of aqueous systems involved in the drilling, completion, workover or production of subterranean oil or gas wells), and the like.
In any oil-in-water emulsion, the amount of oil in the water or aqueous phase or, in the case of a dispersion of a non-aqueous phase the amount of such non-dispersed phase, will vary, considerably, depending upon the industrial application at hand. In the case of emulsions which are frequently found in the oil field and in applications of well completion operations, the oil-in-water emulsion will contain a crude oil content varying from a few parts per million to about 20%, by volume, and even higher.
In treating such emulsified or dispersed aqueous systems for disposal or other uses or recycling, it is necessary to break the emulsified oil-in-water or resolve the dispersion such that the oil phase, or the non-aqueous dispersed phase and the water phase may be separated. The water should be clarified by the resulting demulsification treatment without production of an uncontrollable "floc". While "floc" may always be expected to be produced as a result of a water clarification treatment procedure, such "floc" should be made to be controllable, such that the treated aqueous system can pass certain industrial and/or governmental water clarity tests or specifications.
In the past, those skilled in the art have recognized the use of derivatives of certain amines as de-emulsifiers in water clarification procedures. Typical of such prior art is U.S. Pat. No. 4,689,177, which teaches the use of nitrogen-containing tridithiocarbamic acid compositions as "reverse" demulsifiers. While certain of the materials disclosed in the '177 patent may, or may not, be used satisfactorily to deemulsify certain aqueous systems, it has been found that not all such materials are satisfactory to clarify the water without production of a resultant uncontrollable "floc".
In the present invention, however, it has been found that by selection of a particular amine derivative reacted in an approximate stoichiometric ratio with carbon disulfide, a dithiocarbamate can be utilized to successfully break the emulsion and clarify the water, without the production of an uncontrollable "floc".